Classical philosophy and Darwinian biology are far more compatible than is usually assumed. In fact, looking at either from the standpoint of the other can enrich and deepen our appreciation of both. From a Darwinian point of view, the theories of Plato and Aristotle deserve to be taken very seriously. From the classical point of view, Darwinian biology is much less reductionist than its enemies suppose.

Friday, September 18, 2015

How Group Selection Works

To say that a human being must
breathe, eat, and defecate, all on a regular basis, in order or write poetry,
does not reduce poetry to respiration and digestion; it simply reminds us that
poets are biological beings. Biological
processes such as these may rarely be relevant to the interpretation of poetry
but they are constantly relevant to an historical interpretation of households
and cities. Caesar cannot recline and
enjoy his feasts if food does not come in and poop go out and neither can
Rome.

If you want to understand the
idea of justice, as Plato’s Socrates sets out to do in the Republic, you will
sooner or later have to account for the existence of human souls and human
communities and that cannot be accomplished without evolutionary theory. My position (big surprise) is that the latter
completes Socrates’ account.

I have been reading David Sloan
Wilson’s Does Altruism Exist? It reminded me of a fairy tale I composed
some time ago to illustrate group selection.
I offer it here.

Consider a group of imaginary
primates living and hunting in small groups in an area covered by tall
grass. I’ll call them puds. Some of the primates in each group are taller
than the grass. Others are smaller than
the grass.

Now consider that this population
of puds is subject to two selection pressures.
The puds are preyed upon by a large avian animal. I’ll call it a dragon. Dragons cannot spot a single tall pud but can
easily spot more than a handful when the group is moving. When a dragon descends on a pud group,
however, it can feed on large and small with equal ease. Groups with a lot of tall puds are at a
disadvantage, so that is selection
against those groups.

Within each group, tall puds have
an advantage. They are stronger and can
forcibly mate with more females than their shorter male pud compatriots. So in any group with both tall and short
males, the taller will proliferate over time.
So that is selection against small
puds.

If the groups remain isolated from
one another, the species is on the road to extinction. Every group will eventually have enough
basketball stars to attract a dragon and so every group will be eaten and the
dragons will go on disability.

What will save the puds is that
some of them will survive a dragon attack.
The survivors will find other survivors and form new groups. Groups with more short pud fellows will
survive longer and grow larger, increasing the supply of small puds in the
total population. If, however, every
group has at least a few tall guys, the cycle will continue.

One thing that might alter the trajectory
is if the puds are smart enough to figure this out. A bunch of small puds might realize that the
two tall puds who made it to the founding council are a problem and vote them
off of the island. This rule, whether a
product of pud culture or a slowly evolving disposition, would tilt the playing
field in favor of puds against dragons. How
bad it would be for the latter depends on how tall genes are distributed in the
population.

I thought this up before I knew a
lot about the research into group selection.
I intended it only as a demonstration that group selection was logically
possible. D.S. Wilson’s book gave me an
example that neatly matches my fairy tale.
Pond skaters (Gerridae) are insects that skate across water in search of
prey. The males come in two flavors:
rapists and gentlemen. The former force
themselves on any female they meet. The
latter wait until a female approaches to mate.

Within groups of skaters, the
rapists have an advantage. They mate
more often and produce more offspring.
So their sons proliferate in the group.
However, their appalling behavior doesn’t leave the females with enough
time to feed, so they lay far fewer eggs than they would if they were well
fed. The result is that groups with more
gentleman grow faster than those with more rapists.

What keeps the gentleman in
business is that females have some choice.
When groups are forming, females are more likely to join a group with
more gentlemen. That simple,
biologically trigger preference, rewards chivalry with the precious coin of reproductive
success.

This explains so much. It explains why cooperation is so difficult
and how it is possible. It explains why
rules of justice are necessary among human beings and other social organisms
and how justice is possible.

Something more important now
occurs to me. The balance between group
selection and individual selection can tilt either way. When it tilts toward the group, eventually
you get the assimilation of individual organisms into a new whole, as when a multi-cellular animal emerges from a cooperation of cells. When it tilts the other way, the community
with its social interactions disintegrates into individual competitors.

Human beings are social animals
but we are also individuals. The entire
field of justice and morality emerges from this fact. All human activity, including poetry and
politics, is possible because within group selection and between group
selection balanced out, over a long period of our life on this earth.